The Ku Klux Klan played an active and enduring role in steering southern white voters away from the Democratic Party to the Republican Party, according to a new study.

The white supremacist group resurged to prominence in the 1960s as a reaction to the civil rights movement, and its violent extremism inflamed racial division and polarized communities for generations, according to the study published by the American Sociological Review.

“It encouraged white voters to prioritize the defense of white supremacy when making voting decisions, upending long-standing Democratic Party allegiances,” wrote the study’s authors.

The researchers — David Cunningham, professor and chair of the Department of Sociology at Brandeis University, Rory McVeigh of the University of Notre Dame and Justin Farrell of Yale University — studied county voting records in 10 southern states where the KKK actively recruited members in the 1960s.

Analysis of voting outcomes of five presidential elections between 1960 and 2000 showed a statistically significant increase in GOP voting compared to counties with no established KKK chapter, even after filtering out a range of other factors that could influence voting preferences.

The researchers also found that a poll conducted in 1992, “decades after the Klan’s decline, [showed] conservative racial attitudes strongly predict southerners’ Republican voting, but only in counties where the Klan was organized in the 1960s.”

KKK chapters were more likely to be formed in strongly Democratic counties earlier in the civil rights movement, which reflected the long-standing link between southern Democrats and white supremacists.

But that political bond began unraveling as the national Democratic Party became increasingly aligned with the black civil rights struggle, and many of those former Democratic voters backed Republican Barry Goldwater in 1964 and third-party anti-desegregation candidate George Wallace 1968.

The study found that counties with a Klan chapter were much more likely to back those two candidates, and adjacent counties without an active KKK chapter of their own were also more likely to support Goldwater and Wallace.

“The Klan played an active role in encouraging white southerners to prioritize white supremacy over party loyalty,” wrote the study’s authors.

KKK leaders urged southerners to “form a voting bloc to defeat any n*gger-loving politician that runs for office,” and the group evaluated and supported candidates based on their “authentic whiteness” rather than party ties.

This was a significant change from the Democratic Party loyalty that had assured white political dominance since the end of the Civil War.

“The very idea of uncompromising party loyalty was wedded to the logic of white supremacy,” the researchers found.

The Klan spread its message at rallies that regularly attracted more than a thousand spectators – most of whom were sympathizers or curious onlookers, rather than formal members – and the intense debate over the group’s activities reached residents who didn’t even attend.

Klan organizations were more likely to be formed in populous counties with high rates of home ownership and a higher percentage of black residents, and they attracted more participation in less-prosperous counties where whites were more vulnerable to economic competition.

Goldwater picked up stronger support than fellow Republican Richard Nixon had four years earlier in counties with larger black populations.

“Given the barriers to voting still in place in the South for blacks in 1964, prior to the passage of the Voting Rights Act, this finding reflects high support among white voters in counties were the perceived threat posed by African-Americans to white interests was greatest,” the authors argued.

By the early 1970s, the researchers argued, “it had become increasingly clear that the national Republican Party was more in line with the interest of those opposed to civil rights than was the Democratic Party.”

When all other variables were factored out, the researchers said the average increase in Republican voting between Nixon’s unsuccessful 1960 campaign and Ronald Reagan’s 1980 win was 3.7 percent higher in Klan counties compared to non-Klan counties.

The Klan effect between 1960 and George H.W. Bush’s 1992 unsuccessful campaign was 4.9 percent higher, and 3.4 percent higher in 2000, when his son, George W. Bush, was elected to the White House.

“The wedding of the Klan’s mainly working-class constituency to the Republican Party was no simple feat in light of the strong appeal that Republican candidates hold for wealthy and upper-middle-class white southerners,” the authors argued.

White working-class southerners were more receptive to Republican economic policies because they had already broken ties to the Democratic Party due to its position on civil rights, they argued.

“The Ku Klux Klan did not succeed in defending Jim Crow, but, through its similarly polarizing character, played a role in linking its working-class constituency to a political party that strongly opposes proactive intervention of the federal government to produce greater racial and class-based equality,” the researchers said.